Solenoid isolation valve

ABSTRACT

The disclosure of U.S. patent application Ser. No. 11/161,914 including the specification, drawings and abstract is incorporated herein by reference in its entirely. An improved pilot-operated, “instant-on”, solenoid isolation valve discloses a new fluid passage route to save cost of drilling a longitudinal hole within the primary piston. Also, a new feature of primary piston assembly with a movable seal piston having a specific circumferential surface matching to valve body chamber to restrict fluid from front side into back side of the primary piston to produce pressure difference to induce instant valve open when solenoid is energized initially. It also introduces a channel hole in the flange of the sleeve assembly as a communication channel of supply of gas into the chambers of the back side of primary piston assembly. The diameter of the channel hole is not critical to determine in this new invent. As long as the size of the hole is smaller than that of the bleed hole, it can maintain pressure difference between the front side and back side of primary piston during valve opening operation. In addition, since the pilot piston and the primary piston assembly operate independently, the travel stroke of the primary piston assembly is unconstrained by the input electrical power.

FIELD OF THE INVENTION

The primary application field of the invention relates to fuel systemsfor compressed natural gas (CNG) vehicles or the like. It may be use forother applications, such as high pressure gas filling station.

BACKGROUND OF THE INVENTION

When compressed natural gas or compressed hydrogen gas is stored incylinders at pressure as high as 6,000 psig, without equipped a fuelpump, an electrical solenoid is used to control fuel flow to quicklystart and stop the fueling process. There exist some problems in thecurrent electrically operated pilot-type, “instant-on” solenoid valves,especially during the opening and closing stage of the valve. In theprior arts U.S. Pat. Nos. 5,762,087 and 6,540,204, a ring segregates theprimary piston to form a front side and a back side, where the frontside is in the direction of the outlet. When the solenoid is energized,a pressure difference is created between the front side and the backside and it overcomes the biasing elements to open the solenoid valve.During the opening process, a small ratio of the amount of gas of inletto outlet of the back side of the primary piston is desired, because ithelps to open the valve. However, in this case, such ratio is rathercritical and it can not be easily determined. During the valve closeprocedure, as the pilot piston is trying to adjust itself to a sealposition, the amount of gas leaking from the back side of the primarypiston to the outlet of the valve may be higher than that of supplyingfrom the front side. Hence, the pressure won't be able to build up inthe back side. Under this circumstance, because the spring force can notovercome the pressure difference between the back side and the frontside of the primary piston, the valve might not close eventually.

In this invention, two matching surfaces between the primary pistonassembly and valve body chamber is designed in such a way that the gasflow is restrained from the front side to back side of the primarypiston assembly to create a pressure difference when the solenoidenergizes, so that the valve open instantly. A channel hole isintroduced to maintain the pressure difference between the front sideand the back side of the primary piston assembly while when the valveopens. Unlike the prior arts, during the closing process and when thepilot piston adjusts itself to a seal position, the amount of gasentering the back side of the primary piston assembly is faster than theamount of gas leaking and that since a certain pressure difference ismaintained, the valve can be closed quickly. In either case, the ratioof the amount of gas is not critical.

Another feature disclosed in the present invention is that an axialcenter column mounting in the housing of the valve provides a bleed holeseat and an axial passage being in communication fluid with the outletchamber. The magnetic field generated by the permissible electricalpower of the solenoid will determine the maximum travel stroke of thepilot piston. In this invention, since the pilot piston does not sit onthe primary piston assembly, the stroke of the primary piston is notlimited under such permissible condition.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide asolenoid isolation valve of the above mentioned general type whichavoids the disadvantages of the prior art.

It is also an object of the present invention to provide a solenoidisolation valve that will virtually open instantaneously, by introducingtwo special matching and contacting surfaces on the movable seal pistonand the primary piston chamber to restrain gas flow communicating withgas inlet when the pilot piston starts to open.

It is also an object of the present invention to avoid the difficulty indetermining the ratio of gas flow in and out of the chambers proximatethe pilot piston for opening and closing the valve.

It is also an object of the present invention to provide a solenoidisolation valve in which the stroke of primary piston is not limited bythe stroke of the pilot piston, by introducing an axial center columnmounted in the housing of the valve.

In keeping with these objects and with others which will become apparenthereinafter, one feature of present invention resides, briefly stated ina solenoid isolation valve which has a housing defining a primary pistonchamber and an outlet chamber. Both chambers are in gas communicationwith a primary channel. Both chambers also are in gas communication witha gas inlet and a gas outlet respectively. An axial center column is inthe primary piston chamber to provide the bleed seal seat, the axialpassage, the vent holes, and the slide able support of both the sealpiston and the primary piston. A tubular sleeve assembly with a magneticclosure at one end and connects to the hollow cylindrical flangeprovides the room for the slide of the pilot piston, the seal piston andthe primary piston. The primary piston is received in the seal piston,and both move axially in the empty space of the flange. A special outersurface is designed at the open side of the seal piston being in perfectcontact with the inner surface of the housing, to restrain the gas flowfrom the inlet to create a pressure difference between the front sideand the of the back side of the primary piston. The valve opensinstantly.

When the gas fills into the empty valve, the seal piston moves upslightly to allow gas flow into the chambers of valve, providing anequalization of pressures in chambers and sealing the valve and springforce resumes the seal piston to a closed position. When the solenoid isenergized, pilot piston is moved to open the bleed orifice. The sealpiston restrains the gas flow to decrease the gas pressure in thechambers, so that an instant opening of the valve to a wide-openposition is ensured. While the valve is opened, the bleed orifice drainsgas faster than in-flow in via the channel hole provided in the flange,to maintain the same pressure difference, so that the valve stays open.When the solenoid is de-energized, as the pilot piston adjusts itself toclose the bleed orifice, there will be enough supply of gas via thechannel hole to build up the gas pressure to close the valve.

The novel features which are considered as characteristics for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a solenoid isolation valve ofconfiguration 1 at closed state.

FIG. 2 is a cross-sectional view of a solenoid isolation valve ofconfiguration 1 at opened state.

FIG. 3 is a cross-sectional view of a solenoid isolation valve ofconfiguration 2 at closed state.

DESCRIPTION OF PREFEERED EMBODIMENT

Attention is first directed to FIG. 1, which shows a solenoid isolationvalve in section view. In housing 1, it provides the primary pistonchamber 2 and the outlet chamber 3; both chambers are in gascommunication with each other through the primary channel 4. The primarypiston chamber 2 connects to the gas inlet 9. The outlet chamber 3connects the gas outlet 10.

A non-magnetic tubular sleeve 5 with a magnetic closure 6 at one endconnects to a magnetic hollow cylindrical flange 7. An electrical coil 8around the tubular sleeve 5 for generating the magnetic field.

An axial center column 11 with a circular disk 12 at one end, and ableed hole seat 13 at another end. There are vent holes 14 through thecircular disk 12, parallel to the axis of the axial center column 11.The axial center column 11 mounts into the primary channel 4 withexternal threads on the circular disk 12. The column portion of theaxial center column 11 sits in the primary piston chamber 2. Then, theprimary piston chamber 2 is in gas communication with the outlet chamber3 through the vent holes 14 of the circular disk 12.

A pilot piston 15 is received and axially movable within the tubularsleeve 5. The pilot piston 15 has a sufficiently loose fit within thetubular sleeve 5, to allow gas from one end of the pilot piston 15 toreach the other end. The pilot piston 15 is comprised of a magneticpilot piston body 29 and a pilot seal 30 mounted at the end of pistonbody 29 to achieve a gas-tight seal against the bleed hole seat 13. Thepilot seal 30 is made of soft rubber. A compression spring 16 urges thepilot piston 15 away from the magnetic closure 6 against the bleed holeseat 13 of the axial center column 11 towards the pilot piston closedposition. An axial passage 17 within the axial center column 11 connectsto a bleed orifice 18, close to the bleed hole seat 13. The axialpassage 17 communicates remote from chambers proximate the pilot piston15 with the outlet chamber 3.

A bowl-like seal piston 19 has a front side and a back side. The sealpiston 19 is open at the front side, and a primary piston 20 is receivedwithin the seal piston 19. Both the primary piston 20 and the sealpiston 19 are axially movable within the hollow cylindrical flange 7,and also slide able along the axial center column 11. Since thebowl-like seal piston 19 is made of soft plastic, having a close fitwithin the hollow cylindrical flange 7, it restrains the passage of gasaxially between the seal piston 19 and the hollow cylindrical flange 7,when the seal piston 19 moves axially within the flange 7. A conicalcompression spring 28 urges the bowl-like seal piston 19 and the primarypiston 20 towards the closed position.

A primary seal seat 21 and a primary orifice 31 locate at the boundarybetween the primary piston chamber 2 and the primary channel 4. A curvedspring washer 22 locates in a chamber between the bowl-like seal piston19 and the primary piston 20, urging the primary piston 20 towards theclosed position. The primary piston 20 is comprised of the primarypiston body 32 and a primary seal 33 mounted at the end of the frontside of the primary piston 20. The primary seal 33 is made of plastic.The primary piston 20 operates an opened and a closed position withinthe bowl-like seal piston 19. The primary piston 20 has a front side anda back side. The back side is near the chamber between the seal piston19 and the primary piston 20. When the primary piston 20 is at theclosed position, it stops gas flow from the primary piston chamber 2 tothe vent holes 14 of the circular disk 12 through the primary orifice31. The seal piston 19 and the primary piston 20 are collectively knownas primary piston assembly.

A bowl channel hole 23 is at the bottom side of the bowl-like sealpiston 19, communicating the gas between the empty space of the hollowcylindrical flange 7 and the chamber in between the seal piston 19 andthe primary piston 20. A primary peripheral seal 24 locates between theprimary piston 20 and the axial center column 11, acting to restrain thepassage of gas axially between the primary piston 20 and the axialcenter column 11. The primary peripheral seal 24 is achieved by ano-ring element located in a circumferential recess in an innercylindrical portion of the primary piston body 32. The secondaryperipheral seal 25 locates between the primary piston 20 and thebowl-like seal piston 19, acting to restrain the passage of gas axiallybetween the seal piston 19 and the primary piston 20. The secondaryperipheral seal 25 is achieved by an o-ring element located in acircumferential recess in an outer cylindrical portion of the primarypiston body 32.

A channel hole 26, located in the cylindrical portion of the hollowcylindrical flange 7, perpendicular to the central axis of the flange 7.It communicates gas into the empty space of the flange 7. The outersurface 27 of the bowl-like seal piston 19, located at the front end,and the inner surface of the primary piston chamber 2 are in perfectcontact with each other so that initially the gap between two surfacesrestrains gas from the gas inlet 9 to the primary piston chamber 2 whenthe electrical coil 8 is not activated.

Referring to the FIG. 1, initially, the inlet gas pressurizes the valve.The pressured gas pushes up the bowl-like seal piston 19 to fill allempty chambers in the valve. The gas pressure in the valve is then inequilibrium. The two compression springs 16, 28 and the spring washer 22push the pilot piston 15, the seal piston 19 and the primary piston 20toward the closed position.

Referring to the FIG. 2, when the electrical coil 8 generates a magneticfield, the pilot piston 15 moves towards the closure. The gas reservedin the chambers of the valve is released to the outlet chamber 3 via theaxial passage 17 and vent holes 14 of the axial center column 11, andthe gas in the chambers of the valve drains instantly. It reduces thepressure in the chambers, the pressure difference overcomes the springforces exerted by items 28 and 22, then, both the seal piston 19 and theprimary piston 20 open to allow the gas inlet 9 communicate directlywith outlet chamber 3. Since the size of the channel hole 26 is smallerthan that of the bleed orifice 18, the gas pressure is not able to buildup in the chambers in valve during the valve open operation because theamount of gas exiting the chambers is more than entering. The valvekeeps open.

When the magnetic field ceases, the compression spring 16 pushes thepilot piston 15 to the sealed position. During the sealing procedure,the gas via the channel hole 26 and can supply enough gas to build upthe gas pressure in the chambers near the pilot piston 15. The pilotpiston 15 adjusts itself to seal the bleed orifice 18 completely. Thegas pressure builds up and is in equilibrium in the chambers of thevalve. All compression springs 16, 23 and spring washer 22 push theprimary piston 20 towards the closed position.

Attention is also directed to FIG. 3, which shows another kind ofconfiguration of a solenoid isolation valve in section view. In thisconfiguration, the seal piston 19 is a hollow cylinder, and a primarypiston 20 is received in the seal piston. The compression springs 22pushes the seal piston 19 and the compression 22 pushes the primarypiston 20 towards the closed position respectively. The method ofoperation procedure is similar to the above-mentioned for FIG. 1 and 2.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in the other typesof constructions differing from the types described above.

While the invention has been illustrated and described as embodied insolenoid isolation valve, it is not intended to be limited to the detailshown, since various modifications and structural changes may be madewithout departing in any way from the sprit of the present invention.

1. A solenoid isolation valve assembly for controlling the flow of gasfrom a source of gas to a demand comprising: (a) a housing extendingalong a central axis, defining a primary piston chamber and an outletchamber; the primary piston chamber being in gas communication with theoutlet chamber through a primary channel; (b) a tubular sleeve assemblybeing comprised of a non-ferromagnetic tubular sleeve, having at one enda ferromagnetic closure preventing the escape of gas; at the other end,said non-ferromagnetic tubular sleeve connecting a hollow cylindricalferromagnetic flange with external threads mounting into said primarypiston chamber; an electrical coil around the tubular sleeve assemblyfor generating a magnetic field; a solenoid being comprised of thetubular sleeve assembly and the electrical coil; (c) the primary pistonchamber defining a gas inlet extending perpendicular to the central axisfor directing gas into the housing; said outlet chamber defining a gasoutlet to the demand; (d) an axial center column with a circular disk atone end; a bleed hole seat being defined by the axial center column atthe other end; the circular disk defining vent holes parallel to theaxis of the axial center column; the axial center column mounting intosaid primary channel with external threads on the circular disk; theaxis of the axial center column being parallel to the axis of saidhousing; the column portion end with the bleed hole seat of the axialcenter column sitting in said primary piston chamber; the primary pistonchamber being in gas communication with the outlet chamber through thevent holes of the circular disk; (e) a pilot piston received and axiallymovable within said non-ferromagnetic tubular sleeve for movementtowards and away from the ferromagnetic closure; the pilot piston havinga sufficiently loose fit within the tubular sleeve to allow gas from oneend of the pilot piston to reach the other end thereof; a pilot biasingelement urging the pilot piston away from said ferromagnetic closureagainst the bleed hole seat of the axial center column towards theclosed position; (f) said axial center column defining an axial passagecoaxially; the axial passage including a bleed orifice proximate to thebleed hole seat, the axial passage communicating gas remote fromchambers near the pilot piston with said outlet chamber; (g) a primarypiston assembly being comprised of a seal piston and a primary piston;the primary piston being received within the seal piston; both the sealpiston and the primary piston axially movable within the hollowcylindrical ferromagnetic flange, and slideable along said axial centercolumn; the seal piston made of a material selected from the class ofmaterials known as soft plastic; the seal piston having a close fitwithin the hollow cylindrical ferromagnetic flange to sufficientlyrestrain the passage of gas axially between the seal piston and thehollow cylindrical ferromagnetic flange; primary biasing elements urgingthe primary piston assembly towards the closed position; (h) the primarypiston chamber defining a primary seal seat and a primary orificelocated at the boundary of the primary piston chamber and the primarychannel; the primary piston operating an opened and a closed positionwithin the seal piston; the primary piston assembly having a front sideand a back side; the back side of the primary piston assembly facing inthe direction of the empty space of the hollow cylindrical flange; theprimary piston assembly stopping gas flow from the primary pistonchamber to the vent holes of the circular disk through the primaryorifice when the primary piston assembly is at the closed position; (i)a primary peripheral seal between the primary piston and the axialcenter column, acting to restrain the passage of gas axially between theprimary piston and the axial center column; (j) a secondary peripheralseal between the seal piston and the primary piston, acting to restrainthe passage of gas axially between the seal piston and the primarypiston; (k) the hollow cylindrical ferromagnetic flange defining achannel hole in the cylindrical portion, perpendicular to the centralaxis for communicating gas into the empty space of the hollowcylindrical ferromagnetic flange; (l) the end of said seal pistonproximate the front side of the primary piston assembly having acircumferential outer surface matching and contacting with an innersurface being defined by the primary piston chamber for restraining thesupply from the gas inlet to the primary piston chamber when the valvestarts to open.
 2. The solenoid isolation valve assembly of claim 1,wherein the axis of translational displacement defined by the primarypiston assembly is parallel to the axis of translational displacementdefined by the pilot piston.
 3. The solenoid isolation valve assembly ofclaim 1, wherein: (a) the pilot piston including a pilot piston body anda pilot seal mounted at one side of the piston body to achieve agas-tight seal against said bleed hole seat; (b) the pilot seal made ofa material selected from the class of material known as soft elastomers.4. The solenoid isolation valve assembly of claim 1, wherein: (a) theprimary piston including a primary piston body and a primary sealmounted at the end of the primary piston body facing in the direction ofthe primary seal seat; (b) the primary seal made of a material selectedfrom the class of material known as plastic; (c) said primary peripheralseal is achieved by an o-ring element located in a circumferentialrecess in an inner cylindrical portion of the primary piston body; (d)said secondary peripheral seal is achieved by an o-ring element locatedin a circumferential recess in an outer cylindrical portion of theprimary piston body.
 5. The solenoid isolation valve assembly of claim1, wherein the pilot biasing element is a compression spring.
 6. Thesolenoid isolation valve assembly of claim 1, wherein the primarybiasing elements are a compression spring and a spring washer or twocompression springs.
 7. The solenoid isolation valve assembly of claim1, wherein the end of the seal piston having a tapered circumferentialouter surface to achieve gas-restraining by matching the inner surfaceof the primary piston chamber.
 8. A method of enabling the completeclose and open of the solenoid isolation valve assembly of claim 1,comprising the steps: (a) providing gases from a gas inlet to fill thevalve, an equilibrium is reached when a solenoid is not energized; apilot biasing element urging a pilot piston against a bleed hole seat ofa axial center column; the first primary biasing element pushes a sealpiston of a primary piston assembly against a matching inner surface ofa primary piston chamber for restraining the supply of gas from the gasinlet to the primary piston chamber; the second primary biasing elementsits between the seal piston and a primary piston of the primary pistonassembly or in between a hollow cylindrical ferromagnetic flange and theprimary piston, urging the primary piston against a primary seal seat,so that the valve is in the close state; (b) when the solenoid isenergized, the pilot piston moves towards a ferromagnetic closure of atubular sleeve assembly, thus, opening a bleed orifice of the axialcenter column and releasing the gas reserved in the chambers locatedaround the pilot piston, the back of the primary piston assembly, via anaxial passage of the axial center column to an outlet chamber of ahousing; (c) because of the matching surfaces between the seal pistonand the primary piston chamber are contacted without any clearance, itcreates a pressure difference between two opposite sides of the primarypiston assembly, the primary piston assembly moves away from the primaryseal seat, and allowing direct communication between the primary pistonchamber and the outlet chamber via vent holes in a circular disk of theaxial center column; (d) gas continually being supplied from the primarypiston chamber into all chambers via a channel hole of the hollowcylindrical ferromagnetic flange; the diameter of the channel hole issmaller than that of the bleed orifice of the axial center column; (e)because the diameter of the channel hole is smaller than that of thebleed orifice, the supply of gas in chambers as described in (d) is nomore than that of the bleed out; the valve remains open; (f) when thesolenoid is de-energized, the pilot biasing element urging the pilotpiston to seal the bleed orifice, and the gas pressure is built up toreach an equilibrium between the front side and the back side of theprimary piston assembly. Two primary biasing elements urging the primarypiston assembly to close the valve: the first biasing element pushes theseal piston of the primary piston assembly against the matching innersurface of the primary piston chamber; the second biasing element pushesthe primary piston of the primary piston assembly to seal a primaryorifice to stop the gas flow between the gas inlet and the outletchamber; the valve is closed.